I try to project out my retirement income and at 8% growth over each year what my retirement savings would be like. I have only been trying to reduce my taxable income up until now, and DW and myself have been maxing out TSP/401k for a while now (myself since 23, her the last few years). I have also been maxing out Roth IRA and she started this year as well. I really hadn't thought much about Roth TSP yet as I've been focused on reducing taxes, but now I'm thinking about it, as if we keep working we may have more than enough in taxable retirement to push us into a higher tax bracket, or at least even. If it were even then I guess it's a wash, but what's gotten me more interested lately is that you can still contribute $18k ($18.5k for 2018) to a Roth TSP, which is essentially $22.5k since it's post tax. It would be a stretch to be able to do this and keep with the Roth IRA contributions as well. So I was curious to how many are contributing to a Roth TSP vs traditional TSP. I know military generally have lower taxes and aren't taxed on BAH and other things that make the Roth option more beneficial to them while active duty, I just didn't know if civilians go this route or keep it traditional?

One particular section from the first linked post:"Note the possibility of self-defeating predictions:a) predict high taxable retirement income > contribute to Roth > get low taxable retirement incomeb) predict low taxable retirement income > contribute to traditional > get high taxable retirement income"

If it were even then I guess it's a wash, but what's gotten me more interested lately is that you can still contribute $18k ($18.5k for 2018) to a Roth TSP, which is essentially $22.5k since it's post tax.

Even better, do a traditional TSP for $18k, and use that extra $4.2k for a traditional IRA. The tax savings would likely be enough to max out the additional $1.3k for the traditional. If you still had income to invest, start up a taxable account.

Since you've already accumulated a good bit of traditional money, you could hedge your tax bet and start doing Roth now. This way you have money in both pots and can decide after you retire which bucket to draw from on a yearly basis (by keeping one bucket in the TSP and rolling the other bucket to an IRA when you retire if TSP doesn't fix the withdrawal options sufficiently). This way you don't have to predict the future, just save for it and adjust to it when you get there. So while you may have significantly less income in retirement, no one knows what the tax brackets will be. I prefer to pay the taxes I know now than get blindsided by unknown tax rates later.

Since Roth wasn't an option when I started, I have a decent traditional balance. I jumped on the Roth with both feet and stuck my tail in it when that option became available. If all goes according to plan, the traditional and Roth buckets will be essentially equal. It gives me options.

hmm something to consider for next year. I've been contributing to traditional TSP for 10 years and finally hit max contribution this year. (Balance just passed $200k! ) My spouse will be starting a job in January which will approximately double our income. I thought that meant I should continue with traditional over Roth for tax break but maybe not? Spouse will have some kind of 401k but won't vest for a while and starting from zero.

hmm something to consider for next year. I've been contributing to traditional TSP for 10 years and finally hit max contribution this year. (Balance just passed $200k! ) My spouse will be starting a job in January which will approximately double our income. I thought that meant I should continue with traditional over Roth for tax break but maybe not? Spouse will have some kind of 401k but won't vest for a while and starting from zero.

Yep. Because in theory your salary will continue to increase, so your pension + SS will be significant. I did the math on my situation and only the 2 years before I start collecting SS will I possibly (if the supplement goes away) be in a lower tax bracket than I am now. So add on the TSP and I will be paying the same rate in retirement I'm paying now; even though my retirement income will be significantly less than my current income. I'd rather pay it now while my salary is higher than my projected retirement income. Of course with your spouse in the mix, you could get the current tax advantage of traditional with hers and the future tax benefit of the Roth with yours. Just another way of having two buckets, if that appeals to you.